Am Freitag, den 15.12.2017, 01:45 +0300 schrieb Dmitry Osipenko: > On 15.12.2017 00:41, Lucas Stach wrote: > > Am Montag, den 11.12.2017, 18:26 +0300 schrieb Dmitry Osipenko: > > > On 11.12.2017 17:27, Thierry Reding wrote: > > > > On Mon, Dec 11, 2017 at 04:53:56PM +0300, Dmitry Osipenko > > > > wrote: > > > > > On 11.12.2017 13:13, Thierry Reding wrote: > > > > > > On Mon, Dec 11, 2017 at 02:19:44AM +0300, Dmitry Osipenko > > > > > > wrote: > > > > > > > Add manual HW power management to drivers probe/remove in > > > > > > > order to > > > > > > > not fail in a case of runtime power management being > > > > > > > disabled > > > > > > > in kernel > > > > > > > config. > > > > > > > > > > > > > > Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx> > > > > > > > --- > > > > > > > drivers/gpu/drm/tegra/dc.c | 164 > > > > > > > +++++++++++++++++++++++++++---------------- > > > > > > > drivers/gpu/drm/tegra/dsi.c | 138 > > > > > > > +++++++++++++++++++++-- > > > > > > > ------------- > > > > > > > drivers/gpu/drm/tegra/hdmi.c | 90 ++++++++++++++++----- > > > > > > > --- > > > > > > > drivers/gpu/drm/tegra/sor.c | 103 +++++++++++++++++-- > > > > > > > ---- > > > > > > > ---- > > > > > > > 4 files changed, 310 insertions(+), 185 deletions(-) > > > > > > > > > > > > I think that's the wrong way around. We unconditionally > > > > > > select > > > > > > PM on > > > > > > 64-bit ARM already, and I think we should do the same on > > > > > > 32-bit > > > > > > ARM. > > > > > > There's really no excuse not to enable runtime PM these > > > > > > days. > > > > > > > > > > What is the rational behind enabling PM unconditionally? It > > > > > is > > > > > actually a very > > > > > useful debug feature when there is something wrong with the > > > > > PM. > > > > > It looks like > > > > > Tegra DRM driver is the only driver on Tegra that doesn't > > > > > work > > > > > properly with PM > > > > > being disabled. Please, let's just fix it. > > > > > > > > What's useful about disabling PM? The problem with allowing !PM > > > > is > > > > that > > > > it adds one more combination that needs to be build- and > > > > runtime > > > > tested. > > > > > > As I already stated, disabling PM is very useful for debugging > > > when > > > system hangs > > > unexpectedly. I found it very helpful several times. > > > > This assumes that the bootloader/firmware left the power domains > > powered up. Without PM_GENERIC_DOMAINS, which depends on CONFIG_PM > > the > > kernel has no means to control the state of the power domains. > > Probe > > deferral based on the power domain will also not work, so driver > > may > > probe and try to access power-gated devices, leading to system > > hangs in > > the common case. > > Pre-186 Tegra's do not use generic PM domains, but a custom API. > Meanwhile T186 > always has CONFIG_PM enabled. This is incorrect since a38045121bf4 (soc/tegra: pmc: Add generic PM domain support), i.e. kernel 4.7. Regards, Lucas -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
